1. Field of the Invention
The present invention generally relates to a chip support board structure, and more specifically to a chip support board structure having a block layer on a metal substrate to maintain a paddle with high stability and further avoid the problem of easily peeling off.
2. The Prior Arts
Please refer to FIGS. 1A and 1B for illustrating the first and second examples of the chip support board in the prior arts, respectively. The chip support board 100 shown in FIG. 1A generally comprises a metal substrate 10, a paddle 15 on the metal substrate 10, an insulation layer 30, a circuit layer 40 and a solder resist 60. The insulation layer 30 fills up the space between the paddle 15 and the metal substrate 10, but one surface of the paddle 15 is exposed from the insulation layer 30 such that the surface of the paddle 15 and the insulation layer 30 form a co-plane surface. The circuit layer 40 is formed on the co-plane surface and is connected with the paddle 15. The solder resist 60 is formed on the insulation layer 30 and the circuit layer 40 to cover part of the circuit layer 40 so as to avoid short circuit upon forming the bonding pads (not shown).
As shown in FIG. 1B, the chip support board 150 in the prior arts is varied with respect to the above chip support board 100 by a carbon fiber prepreg cloth 50 embedded in the insulation layer 30 and a conductive layer 55 formed on the carbon fiber prepreg cloth 50. The circuit layer 40 is formed on the co-plane surface which is formed by the paddle 15, the insulation layer 30 and the conductive layer 55 so as to connect with the paddle 15 and the conductive layer 55.
However, one of the shortcomings of the chip support board in the prior arts is that the paddle 15 is generally formed by the etching process on the circuit layer 40, that is, directly formed of the circuit layer 40. It is difficult to maintain the shape, the etching depth and the void depth of the paddle 15 in the mass production because of the same material. This leads to failure of maintaining a smooth surface, and therefore, it is hard to maintain constant the location of the carbon fiber prepreg cloth 50 and the conductive layer 55 formed on the carbon fiber prepreg cloth 50. Additionally, the board is easily peeled off due to external force, thereby affecting the yield rate of the board.